HERA-B: status and commissioning results

HERA-B, an experiment to measure CP violation in the B0→J/ψKS0 decay channel at the HERA proton storage ring at DESY, is a pioneering hadronic B factory using fixed target techniques. In addition to the CP violation measurement, the experiment addresses a wide range of topics in heavy quark physics, complementing the physics accessible at e+e− colliders. The detector design is discussed, putting special emphasis on the needs for the CP violation measurement. Recent commissioning results, from runs using a partially installed detector, are presented.